The solenoid valve for turbine shutdown keeps blowing fuses
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The two sets of compressors in the company have been operating smoothly for about 3 years; however, since the beginning of this year, these two units have stopped operating on average due to the shutdown solenoid valves associated with the quick-shut-off components, which cause the fuses to burn out and lead to an interruption in operation. Our company’s compressor control system is the Beijing Kangjisen TRICON system; in the power circuit of the shutdown solenoid valve, only one pair of passive contacts from the 203 overspeed protection system and the contacts of the interlock shutdown relay are connected in series. Inspections of circuits such as solenoids, instrument cables, power supply systems, and grounding systems were all normal. The power fuse is 1A, and the solenoid valve is powered by 24VDC ； The length of the cable for this circuit is about 300 meters. Since the power of the parking solenoid valve is approximately 6W and the rated current of the fuse is around 0.25A, it can be considered reasonable to use a 1A fuse. However, with two identical derailment incidents occurring, it is suspected that the load current in the power supply circuit was higher than the rated current; yet no accurate measurement was taken due to the high risks associated with measuring such current during the operation of the unit. I had no choice but to replace that insurance with a 3A one. What are your thoughts on this situation? I would appreciate your advice.
Is your 1A fuse of type T slow-blow or F fast-blow? How often should fuses be replaced? Generally, if possible, the fuse should be replaced once a year. Also, the fuses should be from a reputable brand – what brand do you use on site?
The fuse for the ceramic rapid melting system is of type 1A; since the unit was always in operation, a fuse of the same type was installed during the major repair, and the replacement took less than 2 months. As for the brand, I didn’t pay any attention to it.
It is possible to measure current while the device is in operation. FLUK offers a miniature DC current meter, similar to an electrical clamp ammeter, but much smaller in size; it allows for current measurement without the need to disconnect wires.
Is the insulation of the solenoid valve cable in good condition? Is it possible that discharge to ground has caused the fuse to blow?
Check the contacts and terminal blocks.
Find an unused or spare analog input point, connect the current signal in series to it for real-time monitoring; this way, at least when a fuse blows again, the instantaneous current can be measured, and changes in current can also be observed, which facilitates problem analysis
I have also encountered the same issue of the unit tripping.
I have also encountered the same issue of the unit tripping. There are several issues worth discussing: 1) Does the power of the solenoid valve change under different compressor loads? Is 6W the maximum power or the average power? This is something that deserves investigation. 2) In the solenoid valve circuit, in addition to the solenoid valve itself, there are also wire resistances; as a result, the operating voltage across the solenoid valve is less than 24V. Therefore, the actual current in the circuit will be greater than 0.25A. The extent of this increase depends on the ratio between the resistance of the solenoid valve and the wire resistances.
Since the pressure of the hydraulic oil generally does not change much, the power consumption of the stop solenoid valve should also remain relatively constant； The adjustment of the compressor load is independent of the solenoid valve. It is indeed necessary to accurately measure the coil voltage and current in order to select the appropriate fuse.